import os
class grandFather():
    print('我是爷爷')


class Parent(grandFather):
    print('我是父类')


class SubClass(Parent):
    print('我是子类')

#即搜索的顺序就是所谓的「方法解析顺序」（Method Resolution Order，或MRO
print (SubClass.__mro__)
sub = SubClass()
print (help (os))